1. Field of the Invention
The present invention relates generally to end fittings for flexible metallic conduits in which electric cables are received and, more particularly, to improvements in protecting such end fittings from deleterious environmental conditions such as moisture.
2. Description of the Prior Art
End fittings for flexible plastic-coated, liquid-tight metallic conduits are well known and have been described, for example, in U.S. Pat. No. 3,791,680. The end fitting typically comprises a tubular body having an externally threaded end adapted to be screwed into an end of a flexible metallic conduit. A sleeve having an externally threaded portion is mounted on the other end of the tubular body, and is screwed into a female threaded metallic support structure. A tubular collar is mounted on the body and concentrically surrounds the externally threaded end thereof to define an annular space therewith in which the conduit end is received. In order to prevent ingress of water into the conduit, an O-ring seal is mounted between the sleeve and the collar, as well as providing an annular projection on the interior of the collar for engagement with the exterior plastic surface of the conduit within the annular space.
Although generally satisfactory for their intended purpose, it has been found that the prior art end fittings are not sufficiently protected from water damage. The collar projection does not reliably prevent moisture from entering the interior of the conduit. Moreover, the O-ring seal likewise does not adequately prevent ingress of water into the conduit because the seal is moved when the collar is rotated. The disturbance of the O-ring seal during the collar movement and the resulting wear of the O-ring exposes the interior of the conduit to moisture.